1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to a service provided by a home network device, and more particularly, to allowing an external device to use a local service provided by a home network device in a home network.
2. Description of Related Art
A web service technique allows systems distributed in the web (World-Wide Web) to provide interoperable services independent of platform, programming languages, or the like. The web service can be implemented by using a standard such as XML (extensible markup language), SOAP (simple object access protocol), WSDL (web services description language), and UDDI (universal description, discovery, and integration) standards. FIG. 1 is a conceptual view for explaining a procedure for providing the web service. Referring to FIG. 1, a web service is basically constructed with a service provider, a service client, and a service registry. First, the service provider registers service information in the service registry such as a UDDI registry, and the service client acquires the service information from the service registry. More specifically, the service client acquires an address of a site having a web-service-described document, that is, a WSDL file in which the service is described. After that, the service client downloads the WSDL file for the service. Here, the WSDL document or file is a descriptive specification for service, and the service client uses the WSDL document to acquire information for calling the service. More specifically, the service client which downloads the WSDL file generates a SOAP message for the service call by using the information in the WSDL file. The service client transmits the SOAP message to the service provider to call the service.
This web service technique is used for simple services such as a zip code searching service and a content providing service or for complicated services such as a B2B (business to business) transaction service. Recently, such a web service technique has been used for home network devices. As home network devices such as digital TVs, digital audios, and digital printers are constructed in an intelligent manner in the network, techniques are needed for accessing the home-network-device services provided by the home network devices using the web service so as to control the home network devices and share content.
In this case, a home network device must install a web service engine directly so as to provide its services through the web service. The web service engine denotes a series of software applications for such basic web-service-associated techniques such as XML, SOAP, and WSDL techniques.
FIGS. 2 and 3 are views for explaining conventional procedures for providing a home-network-device service to an external device of a home network. FIG. 2 shows the case where a media server in the home network directly provides a home-network-device service to an external client. In this case, an engine required for providing the web service is directly installed in the home network device. Like this, the home network device that provides the web service must directly provide a WSDL document, that is, a specification of the home network device service to the external device. Therefore, the home network device can process a service call transmitted in the form of a SOAP message. Namely, when the home network device installs the web service engine supporting the XML, SOAP, and WSDL standards, the home network device can provide the web service without requiring the support of other devices.
FIG. 3 shows the case where a home network device providing a home network device service does not have a public IP (Internet Protocol) address. In this case, the home network device having a private IP address provides the home network device service to an external device through a home gateway having a public IP address. The home gateway simply performs an address conversion process and routes a message which was transmitted during service calling and performs return processing between the external device and the home network device. In this case, the home network device must also install the web service engine directly.
Although most of the currently-provided web services employ only the basic standards such as XML, SOAP, and WSDL standards, technical requirements associated with high grade techniques such as securities, service policies, and reliable messaging for the web services must be taken in consideration for the future. In order to satisfy such technical requirements, all the home network devices on the home network must install the web service engines that support the aforementioned high grade techniques. Accordingly, the computing resources or disc resources may be wastefully used because of the need to install the web service engines.
In particular, devices having a relatively small amount of resources cannot install such web service engines directly.